Ultracentrifugation Techniques for the Ordering of Nanoparticles

Abstract

A centrifugal field can provide an external force for the ordering of nanoparticles. Especially with the knowledge from in-situ characterization by analytical (ultra)centrifugation, nanoparticle ordering can be rationally realized in preparative (ultra)centrifugation. This review summarizes the work back to the 1990s, where intuitive use of centrifugation was achieved for the fabrication of colloidal crystals to the very recent work where analytical (ultra)centrifugation is employed to tailor-make concentration gradients for advanced materials. This review is divided into three main parts. In the introduction part, the history of ordering microbeads in gravity is discussed and with the size of particles reduced to nanometers, a centrifugal field is necessary. In the next part, the research on the ordering of nanoparticles in analytical and preparative centrifugation in recent decades is described. In the last part, the applications of the functional materials, fabricated from centrifugation-induced nanoparticle superstructures are briefly discussed.

Experimental Method to Distinguish between a Solution and a Suspension

“…The PS NPs dispersion of 17 mg mL −1 was loaded into the ultracentrifuge and the sedimentation-diffusion equilibria were reached at different speeds (2500, 3000, and 3500 rpm). [25,26] The EOS plots for different angular velocities were then calculated and plotted, as shown in Figure 2a. At a lower number density than ≈1E20 m −3 (conc = 10 mg mL −1 ), the EOS are all collapsed in a single master curve indicating solution behavior.…”

How to Characterize the Protein Structure and Polymer Conformation in Protein‐Polymer Conjugates – a Perspective

“…[79] The right part of the equation arises from the Stokes-Einstein relationship defining the diffusion coefficient D to be proportional to the frictional force f. This equation can be rearranged and solved for the molar mass based on the sedimentation behavior. [48,[77][78][79][80] Even though the Svedberg equation provides a basic theoretical understanding of the AUC technique, the Lamm equation is used for the analysis of sedimentation velocity. It describes the time evolution of the radial concentration distribution c(r,t) during sedimentation within a sector-shaped cell.…”

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